e.g. in
artificial intelligence, WHILE heuristic searching, after a few
tree-depths,
variable (ref) might prompt formula
with
error;

e.g. in automata theory, after
a few iterations,
variable (ref) might prompt formula
with
error;

e.g. in
programming languages,
equal sign is assignment
operator,
doko WHERE right side of equal sign is going to be assigned into left
side of equal sign; after a few
lines
of code,
variable (ref) might prompt formula
with
error;